Fundamentals
Mathematics
section .text global is_square ; C-style declaration: ``_Bool is_square();`` is_square: CVTSI2SS xmm0, rdi ; sqrt takes a ``double`` as its argument, so converting rdi to ``double`` first SQRTSS xmm0, xmm0 ; now, XMM0 = sqrt(XMM0 CVTSS2SI rax, xmm0 ; RAX = (int) XMM0 MUL rax ; RAX *= RAX XOR rax, rdi ; if this XOR evaluates to 0, then RAX == RDI SETZ al ; in which case you set the lower 8 bits of AX to 00000001, i.e. "true" RET ; return to the caller- section .text
- global is_square ; C-style declaration: ``_Bool is_square();``
extern sqrt ; C-style declaration: ``double sqrt(double);``- is_square:
cvtsi2sd xmm0, rdi ; sqrt takes a ``double`` as its argument, so converting rdi to ``double`` firstcall sqrt ; now, XMM0 = sqrt(XMM0)cvtsd2si rax, xmm0 ; RAX = (int) XMM0mul rax ; RAX *= RAXxor rax, rdi ; if this XOR evaluates to 0, then RAX == RDIsetz al ; in which case you set the lower 8 bits of AX to 00000001, i.e. "true"ret ; return to the caller- CVTSI2SS xmm0, rdi ; sqrt takes a ``double`` as its argument, so converting rdi to ``double`` first
- SQRTSS xmm0, xmm0 ; now, XMM0 = sqrt(XMM0
- CVTSS2SI rax, xmm0 ; RAX = (int) XMM0
- MUL rax ; RAX *= RAX
- XOR rax, rdi ; if this XOR evaluates to 0, then RAX == RDI
- SETZ al ; in which case you set the lower 8 bits of AX to 00000001, i.e. "true"
- RET ; return to the caller